#include <iostream>

/**
 * 小写字母
 * 
 */
int main() {
    int num;

    std::cin >> num;

    if (num >= 1 && num <= 26) {
        char c = (char)('a' + num - 1);
        std::cout << c;

    }
    else {
        std::cout << "Not exist";
    }
    return 0;
}
